Multiple-glazed breather windows

ABSTRACT

A multiple-glazed unit provided with breather apparatus comprising a capillary tube connected to an elongated column of desiccant material.

United States Patent [1 1 Stewart et al.

MULTIPLE-GLAZED BREATHER WINDOWS Inventors: John L. Stewart, Apollo;George H. Bowser, New Kensingston, both of Pa.

Assignee: PPG Industries, Inc., Pittsburgh,

Filed: July 14, 1972 Appl. No.: 271,889

Related US. Application Data Continuation of Ser. No. 70,840, Sept. 9,1970, abandoned.

US. Cl. 52/172 Int. Cl E061) 7/12 Field of Search 52/172, 616

[ Nov. 13, 1973 [56] References Cited UNITED STATES PATENTS 2,306,32912/1942 Baldwin 52/172 2,885,746 5/1959 Gura.... 52/l72 3,387,416 6/1968Martin..... 52/397 3,570,201 3/1973 Barroero 52/172 PrimaryExaminer.l0hn E. Murtagh Attorney-Russell A. Eberly [5 7] ABSTRACT Amultiple-glazed unit provided with breather apparatus comprising acapillary tube connected to an elongated column of desiccant material.

10 Claims, 4 Drawing Figures PAIENIEDunv 13 I973 SHEET 10F 2 INVENTORSJOHN L. sw m er GEORGE Ban/5.6g W 4 'iymm ATTORNEYS PATENTEUHBV 13 ms3771, 276

SHEET 2 CF 2 INVENTORS JOHN L. srewnm' 20 50 5+ 30 1 3e 52 ,y, lav/56bFl0.4 I M14 5 ATTORNEX;

MULTIPLE-GLAZED BREATHER WINDOWS This application is a continuation ofapplication Ser. No. 70,840, filed Sept. 9, 1970, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a novelmultiple-glazed unit and, more specifically, to a multiple-glazed unitprovided with a breather device. In particular, the invention relates tomultiple glazed units provided with a breather device or apparatuscomprising a length of capillary tubing connected to an elongated columnof desiccant material. In accordance with the invention, a free end ofthe capillary tube is in open communication with the air surrounding theunit while the desiccant column, to which the capillary tube isconnected at its opposite end, is in communication with the enclosed,insulating space of the multiple-glazed unit.

In the past, various types of breather devices have been used onmultiple-glazed units. One such breather device is fully disclosed inU.S. Pat. No. 3,838,809, assigned to the assignee of the presentinvention. In accordance with the aforementioned patent, amultipleglazed unit is constructed comprising a plurality of glasssheets separated at their marginaledges by a hollow spacer elementcontaining a desiccant material, an elongated strip of mastic in sealingcontact with the edges of the glass sheets and the spacer element and apressure sensitive tape covering the strip of mastic. The unit isprovided with an aperture or aligned opening through the tape, masticand outer wall of the spacer element, to connect the atmosphere with thedesiccant, and at least one other opening through the inner wall of thespacer element communicating with the insulating space of the unit. Theopenings or apertures permit the unit to breathe through the desiccantmaterial due to changes of atmospheric conditions.

Although the aforementioned type of unit construction is useful, it hasbeen found that it possesses a number of inherent deficiencies. Forexample, it has been found that the breather opening through the tape,mastic, and outer wall of the spacer element can be blocked, obstructedor pressed closed either by inadvertent or careless handling or byforeign material collecting therein. Moreover, the desiccant materialmay be caused to adsorb a considerable amount of moisture duringbreathing, such that the available quantity of desiccant to keep theunit dry is substantially diminished. Also, if the aperture through thetape, mastic, and outer wall of the spacer element is too large, liquidmoisture from condensation, rain or leakage around the perimeter of theunit can enter this aperture causing a rapid reduction in the units dewpoint over what might be expected due solely to moisture vapor diffusionfrom changes in atmospheric conditions of temperature, barometricpressure, and humidity.

Accordingly, it is an object of this invention to provide an improvedbreather device for multiple glazed units such that the above-mentionedproblems are eliminated or substantially reduced. In accordance with theinvention, this object is accomplished by providing multiple glazedunits with a breather device comprised of a capillary tube connected toa column of desiccant, so that a free end of the capillary tube is inopen communication with the air surrounding the unit while the desiccantcolumn, to which the capillary tube is connected at its opposite end, isin communication with the enclosed, insulating space of the unit.

The foregoing and other objects, features and advantages of the presentinvention will become more apparent from that which follows, when takenin conjunction with the drawings, in which:

FIG. 1 is a perspective view of a multiple-glazed unit constructed inaccordance with this invention;

FIG. 2 is a cross-section along the line IIII of FlG. 1 showing detailsof a preferred edge construction incorporating the breather device ofthis invention;

FIG. 3 is a fragmentary perspective view, partly in section and partlybroken away, of a side edge of the unit of FIG. 1 showing furtherdetails of a preferred embodiment of this invention; and

FIG. 4 is a cross-section similar to that of FIG. 2 showing details ofanother embodiment of this invention.

Illustrated in FIGS. 1 to 4 are acoustical multipleglazed unitconstructions that advantageously employ the breather device of thisinvention in their structures. Shown in FIGS. 1 to 3 are details of onepreferred acoustical multiple-glazed unit 10 in which glass sheets 12and 14 are of unequal thickness to achieve a mismatch of their resonentfrequencies, hence better reduction of sound transmission through theunit. Also, glass sheets 12 and 14 are spaced apart to provide aninsulating space therebetween of about 1 inch or greater, preferablyfrom about 2 inches to about 4 inches, to enhance sound transmissionloss through the unit. The marginal edge portions of the glass sheetsare rigidly supported at the desired spaced apart distance by aperimeter spacer channel 16 adhered by a layer or bead ofmoisture-resistant, air-impermeable mastic 18 to the marginal edgeportions of both glass sheets.

Spacer channel 16 is preferably composed of aluminum or galvanized steeland, in the embodiment shown, has an essentially U-shaped cross-section.As shown, the web 20 of spacer channel 16 is disposed adjacent theperimeter of the unit and the flanges or legs 22 of the U-channel extendinwardly of the unit therefrom. Flanges 22 are preferably L-shaped andtheir free ends are disposed in opposed, spaced relation to each other.

Inserted within spacer channel 16 and extending essentially coextensivein length with each side of the unit are four abutting lengths ofdehydrator element 24. The composition of dehydrator element 24 is nowfully disclosed in applicants assignees U.S. application Ser. No.42,712, the disclosure of which is intended to be incorporated herein byreference. Broadly, dehydrator element 24 comprises a desiccant materialdispersed in a matrix of moisture vapor transmittable material, such asa thermoplastic, block copolymer of styrenebutadiene rubber as is nowdisclosed in U.S. Pat. No. 3,265,765.

Dehydrator element 24, as shown, preferably has a modified U-shapedcross-section, such that when inserted in spacer channel 16 an elongatedspace 26 is defined between dehydrator element 24 and the web 20 ofspacer channel 16. Residing in this space 26 is an The tube 32 is shownclosed at its upper end with a small piece of moisture-resistant,air-impermeable mastic 38 and at its lower end with a piece ofair-permeable felt 40 or the like. Capillary tube 30 is fixed in placewith an end portion 42 connected to or in communication with desiccantcolumn 28 by means of a layer or bead of moisture-resistant,air-impermeable mastic 44 adhered or bonded to tube end portion 42, theweb 20 of spacer channel 16, the peripheral edges of the glass sheets 12and 14 and marginal edge portions of the outer faces of the glasssheets. The free end 46 of capillary tube 30 extends downwardly, outsidethe layer of mastic 44, for a length of about 3 to 12 inches to helpminimize moisture vapor diffusion during breathing. A capillary tube 30having an inside diameter of about 0.025 inch has been found to besatisfactory.

Channeling 48 of essentially U-shaped cross-section extends completelyaround the perimeter of the unit to protect its edges and to protectcapillary tube 30. Channeling 48 is comprised of several channelsections that are joined or butted together at their ends. As shown, thefree end 46 of capillary tube 30 resides in a space 50 defined betweenmastic layer 44 and the web 52 of channeling 48. Since, in theembodiment shown, channeling'48 is comprised of butted channel sections,air may ingress of egress through these butt joints and pass throughcapillary tube 30 and desiccant column 28 to permit the insulating spacebetween glass sheets 12 and 14 to breathe.

FIG. 4 depicts a cross-section of another embodiment of this invention.In this embodiment, in lieu of dehydrator element 24, bags of desiccant54 (one of which is shown) are placed in spacer channel 16, the channel16 is filled with an air permeable material 56, such as fiber glass orpolyurethane foam and the channel is closed with a perforated orforaminous metal strip 58. In all other respects and, in particular,with regard to the breather device 29 of this invention, theconstruction of the embodiment of FIG. 4 is identical to that of FIGS. 1to 3.

EXAMPLE The following deals with a means of determining the length ofthe desiccant column required for a multipleglazed breather window ofthis invention.

Statistically, it has been determined that for a maximum number ofdesign conditions the minimum amount of desiccant required is thatneeded to adsorb the moisture entering the unit at 85 F and 50 percentrelative humidity for one air space volume change created by abarometric change of 1.0 inch of mercury and a F change in airtemperature. Accordingly, consider a unit 74 inches X 90 inches with a 4inch air space. Using the perfect gas equation:

where V original air space volume 74 inches X 90 inches X4 inches/172815.42 ft T, original sealing temperature 75 F P, original sealingpressure 30.5 inches of mercury V, design volume T, design temperature85 F P, design pressure 29.5 inches of mercury V, 16.24. Therefore, AVV, V, 0.82 ft Air density 0.07285 pounds of dry air/ft Pounds of dryair/AV 0.82 X 0.07285 0.05974 pounds Humidity ratio 0.013 pounds ofwater/pound of dry air Pounds of water/AV 0.0594 X 0.013 0.000776 poundsSilica gel adsorbs four percent of its weight at 0 F dew point. Theminimum amount of silica gel required for one air space volume changeis:

Silicia gel (0.000776 X 454)/0.04 8.808 grams A 1/4 inch X 1/4 inch tubecontains 1.22 grams of silica gel per inch.

Minimum length of desiccant column 8.808/1.22 7.2 inches It isrecommended that a safety factor of 10 be used and, therefore, a columnof desiccant of 7.2 X 10 72 inches is required. Accordingly, therecommended amount of desiccant required in a breather column is thatamount which will adsorb 10 times the quantity of moisture entering theunit from one air space volume change based on the specified designconditions.

Although the foregoing disclosure has been made in connection withacoustical window units, it should be apparent that the breather deviceof this invention may be used with other multiple-glazed units as well.Acoustical multiple-glazed units were selected for this disclosurebecause, due to their larger enclosed volume than standard units, e.g.,up to 1 inch thick, they are more susceptible to breakage if they arenot provided with a breather device. Also, it should be understood thatthe glass sheets or glass panels of a typical, transparent,multiple-glazed unit of the invention may be clear, tinted (colored),coated or coated and tinted. In connection with transparent tinted,coated or coated and tinted glass, an advantage of the use of thebreather device of this invention is that it keeps the glass sheets orpanels flat regardless of changes in atmospheric condi tions. Bowedglass, resulting from a pressure difference between the inside and theoutside of a multiple-glazed unit, causes light to reflect unevenly,thus distorting the uniformity of appearance and color of a unit. Bymaintaining the glass flat with the use of the breather device of thisinvention, the uniformity of appearance and color of a multiple-glazedunit, particularly a unit having an outer glass sheet coated with atransparent reflective film, is greatly enhanced.

Although the present invention has been described with particularreference to the specific details of certain embodiments thereof, it isnot intended that such details shall be regarded as limitations on thescope of the invention except insofar as included in the accompanyingclaims.

We claim:

1. In a glazing unit comprised of a pair of rigid sheets supported inopposed, spaced relation to each other by perimeter, marginal edgespacer means defining with said sheets an enclosed space therebetween,said perimeter spacer means having a dehydrator carried thereby incommunication with said enclosed space, the improvement which comprisesa breather device comprising:

an elongated tube filled with a column of desiccant supported by saidperimeter spacer means, said elongated tube having a first opening inthe wall of said tube adjacent one end thereof and located in theenclosed space of said unit adjacent said dehydrator, and a secondopening in the wall of said tube spaced from said first opening andadjacent the other end of said elongated tube, and

an elongated, open-ended capillary tube having one end thereof connectedto said elongated tube at said second-named opening therein and theother end thereof exposed and open to the atmosphere surrounding saidglazed unit to provide an open passage for air between the enclosedspace of said glazed unit and the atmosphere surrounding said unit,

whereby the atmosphere surrounding said glazed unit is free to passthrough said elongated, open-ended capillary tube and throughsubstantially the entire column of desiccant within said elongated tubeinto the enclosed space of said glazed unit.

2. The glazing unit of claim 1 in which the dehydrator comprises adesiccant material dispersed in a matrix of moisture vapor transmittablematerial.

3. The glazing unit of claim 1 in which the dehydrator comprises bags ofdesiccant material.

4. The glazing unit of claim 2 which further includes sections ofchanneling disposed about the perimeter of the unit and wherein saidcapillary tube has a free end residing in a space defined between saidchanneling and adjacent edge portions of said unit.

5. The glazing unit of claim 3 which further includes sections ofchanneling disposed about the permimeter of the unit and wherein saidcapillary tube has a free end residing in a space defined between saidchanneling and adjacent edge portions of said unit.

6. The glazing unit of claim 3 wherein said spacer means comprises achannel member containing an air permeable material and said channelmember is closed on a side facing said enclosed space with a foraminousstrip.

7. The glazing unit of claim 1 wherein at least one of said rigid sheetsis comprised of tinted glass.

8. The glazing unit of claim 1 wherein at least one of said rigid sheetsis comprised of glass coated with a transparent, reflective film.

9. In a glazing unit comprised of a pair of rigid sheets supported inopposed, spaced relation to each other by perimeter, marginal edgespacer means defining with said sheets an enclosed space therebetween,said perimeter spacer means having a dehydrator carried thereby incommunication with said enclosed space, the improvement which comprisesa breather device comprising:

an elongated tube filled with a column of desiccant,

said elongated tube being separate from and located adjacent saidperimeter spacer means and having a first opening adjacent one endthereof located in communication with the enclosed space of said unitadjacent said spacer means, and a second opening spaced from said firstopening and located adjacent the other end of said elongated tube incommunication with and open to the atmosphere surrounding said unit toprovide an open passage for air between the enclosed space of said unitand the atmosphere surrounding said unit,

whereby air from within the enclosed space of said unit and from theatmosphere surrounding said unit is free to pass through substantiallythe entire column of desiccant within said elongated tube.

10. The glazing unit of claim 9 which further includes an elongatedopen-ended capillary tube having one end thereof connected to saidelongated tube at said second-named opening therein and the other endthereof exposed and open to the atmosphere surrounding said unit tofurther provide said open passage for air between the enclosed space ofsaid unit and the atmosphere surrounding said unit,

whereby air from within the enclosed space of said unit and from theatmosphere surrounding said unit is free to pass through said elongatedopen-ended capillary tube and through substantially the entire column ofdesiccant within said elongated tube.

UNITED STATES PATENT. OFFICE CERTIFICATE OF CORRECTION Patent No.3,771,276 Dated November 13, 1973 Inventor(s) Jghn 1,, Stewart andGeorge H. Bgmser It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

In the References Cited "2,306,329" should be ---2,3o 6,32 7

Column 1, line 20, '3,838,809" should be -2,838,809--.

Signed and sealed this l8th day of June 1971;.

(SEAL) Attest:

EDWARD H.FLETCHER,JR. (2. MARSHALL-DANE I Attesting Officer Commissionerof Patents FORM PO-IOSO (10-69) u co c 376.p59

\ v 1: us GOVERNMENT PRINTING OFFICE "n o-su-au,

1. In a glazing unit comprised of a pair of rigid sheets supported inopposed, spaced relation to each other by perimeter, marginal edgespacer means defining with said sheets an enclosed space therebetween,said perimeter spacer means having a dehydrator carried thereby incommunication with said enclosed space, the improvement which comprisesa breather device comprising: an elongated tube filled with a column ofdesiccant supported by said perimeter spacer means, said elongated tubehaving a first opening in the wall of said tube adjacent one end thereofand located in the enclosed space of said unit adjacent said dehydrator,and a second opening in the wall of said tube spaced from said firstopening and adjacent the other end of said elongated tube, and anelongated, open-ended capillary tube having one end thereof connected tosaid elongated tube at said second-named opening therein and the otherend thereof exposed and open to the atmosphere surrounding said glazedunit to provide an open passage for air between the enclosed space ofsaid glazed unit and the atmosphere surrounding said unit, whereby theatmosphere surrounding said glazed unit is free to pass through saidelongated, open-ended capillary tube and through substantially theentire column of desiccant within said elongated tube into the enclosedspace of said glazed unit.
 2. The glazing unit of claim 1 in which thedehydrator comprises a desiccant material dispersed in a matrix ofmoisture vapor transmittable material.
 3. The glazing unit of claim 1 inwhich the dehydrator comprises bags of desiccant material.
 4. Theglazing unit of claim 2 which further includes sections of channelingdisposed about the perimeter of the unit and wherein said capillary tubehas a free end residing in a space defined between said channeling andadjacent edge portions of said unit.
 5. The glazing unit of claim 3which further includes sections of channeling dIsposed about thepermimeter of the unit and wherein said capillary tube has a free endresiding in a space defined between said channeling and adjacent edgeportions of said unit.
 6. The glazing unit of claim 3 wherein saidspacer means comprises a channel member containing an air permeablematerial and said channel member is closed on a side facing saidenclosed space with a foraminous strip.
 7. The glazing unit of claim 1wherein at least one of said rigid sheets is comprised of tinted glass.8. The glazing unit of claim 1 wherein at least one of said rigid sheetsis comprised of glass coated with a transparent, reflective film.
 9. Ina glazing unit comprised of a pair of rigid sheets supported in opposed,spaced relation to each other by perimeter, marginal edge spacer meansdefining with said sheets an enclosed space therebetween, said perimeterspacer means having a dehydrator carried thereby in communication withsaid enclosed space, the improvement which comprises a breather devicecomprising: an elongated tube filled with a column of desiccant, saidelongated tube being separate from and located adjacent said perimeterspacer means and having a first opening adjacent one end thereof locatedin communication with the enclosed space of said unit adjacent saidspacer means, and a second opening spaced from said first opening andlocated adjacent the other end of said elongated tube in communicationwith and open to the atmosphere surrounding said unit to provide an openpassage for air between the enclosed space of said unit and theatmosphere surrounding said unit, whereby air from within the enclosedspace of said unit and from the atmosphere surrounding said unit is freeto pass through substantially the entire column of desiccant within saidelongated tube.
 10. The glazing unit of claim 9 which further includesan elongated open-ended capillary tube having one end thereof connectedto said elongated tube at said second-named opening therein and theother end thereof exposed and open to the atmosphere surrounding saidunit to further provide said open passage for air between the enclosedspace of said unit and the atmosphere surrounding said unit, whereby airfrom within the enclosed space of said unit and from the atmospheresurrounding said unit is free to pass through said elongated open-endedcapillary tube and through substantially the entire column of desiccantwithin said elongated tube.